1. Field of the Invention
This invention relates to the removal of wood dust and similar debris from multiple work stations within a workshop.
2. Description of the Related Art
One of the recognized hazards of working with power tools is that such tools generate considerable amounts of dust from the material being worked. In the case of most home workshops, the predominant dust material is wood dust, which the Environmental Protection Agency has classified as harmful because inhalation of wood dust can cause respiratory problems. In addition, wood dust can also cause eye irritation, and accumulation of moderate quantities of wood dust on the floor of a workshop can present a slipping hazard. The risk of dust inhalation is greatest when the tool operator stands alongside the running tool as it generates more dust.
In addition to the use of personal protective equipment such as dust masks and goggles, a number of mechanical solutions have been proposed to address the problem of workshop dust. Many of these solutions are based on the use of a suction apparatus, such as a vacuum cleaner, to draw dust away from the work station and operator. A typical solution involves the direct connection of a shop vacuum cleaner to a funnel-shaped collector affixed to the work surface of the power tool. But most workshops contain more than one tool, and it would be expensive in terms of both cost and shop space to provide a separate vacuum cleaner for each machine. It would be similarly inefficient in terms of time or effort for the operator to have to move the vacuum cleaner from machine to machine as he proceeds with the steps of a project.
A number of alternatives are known for providing dust collection systems that allow the operator to selectively apply vacuum to one or more tools from among the several in his workshop. One alternative which has generated considerable attention is the use of a rotating disc valve, as disclosed by Albert M. Best in U.S. Pat. No. 4,977,638. The valve consists of two horizontal circular plates: a fixed upper plate containing multiple vacuum inlet ports arranged in a circle about the plate, and a rotating lower plate containing a single passthrough port connected to the vacuum source. The operator selects the tool to which he wishes to apply vacuum by rotating the lower plate to align the passthrough port with one of the inlet ports in the upper plate. The inlet ports are connected individually to the tools in the workshop, which requires considerable use of rigid or flexible ducts.
A second alternative is a manifold-type vacuum distribution system such as that depicted and described in U.S. Pat. No. 5,606,767 (text column 2 and FIG. 2). This system employs a single wall-mounted main vacuum duct or manifold, with the vacuum source attached at one end. The other end of the manifold is completed with an end inlet fitting, typically a coupling or elbow, connected by flexible hose to the last tool in line along the manifold. Inlet branch fittings are provided in the manifold as needed to connect additional tools. These fittings have a straight path along the manifold and a curved branch path for admitting dust from one of the tools. The curved branch helps to prevent dust flowing from upstream in the manifold from entering the branch or depositing at its edge. Each tool is provided with an individual sliding-gate shutoff valve so that vacuum may be applied at the work surface of the tool only when required. The presence of individual valves allows the operator to operate one, several, or all of the tools in his shop at the same time, which is not possible with the rotating disc valve. However, the collection efficiency necessarily drops as vacuum is applied to each additional tool. Even with only one tool operating at a time, collection efficiency drops with increasing duct length between the vacuum source and the tool in use. Furthermore, the requirement that the vacuum source be located at the end of the manifold significantly limits the ability of the operator to arrange the tools in his workshop to his liking or to conserve space.
The present invention is directed to overcoming, or at least reducing the effects of, problems associated with the prior art.